-l : -l (unobserved planes) = 164° 22’
The species is related in form to Vivianite, in which
a : b : 2c = 1.0792 : 1 : 2.614.
The crystals of the two species are also alike in the perfect and pearly clinodiagonal cleavage.
On new Californian Marine Shells. No. II.
BY PHILIP P. CARPENTER, PH. D., OF WARRINGTON, ENGLAND.
Genus Collonia, Gray, 1852.
This genus was established (in English) by Dr. Gray, for Turbinate shells having an “operculum circular, with many gradually enlarged whirls, with a convex external rib and central pit.” The type (still appearing as such in the B. M. Col.) is a smooth fossil from Grignon, = Delphinula marginata, Lam., with a keeled and crenated umbilicus, like Phillippia. Another (African) shell is joined to the diagnosis, with the following brief description: “C. striata, Gray. Shell red, white marbled, striated.” It is quoted by Phillippi, Handb. Conch. p. 206, who assigns as a type T. sanguineus, Linn. For this species and its congeners, we now propose a subgenus Leptonyx, as they do not agree with the type. The genus was reconstituted by Messrs. Adams, Gen. i. 396 for shells with “imperforate axis and contracted aperture:” the description of the operculum being copied from Gray. The type is now “C. marginata, Nutt.” pl. 44, f. 2, the operculum of which is figured as with few whirls. The same description and figure are given in Chenu, Manuel i. 348, f. 2560. The error seems to have arisen thus. Mr. H. Adams (who acted for the ‘firm’ during his brother’s long absence in Japan,) probably took Gray’s C. marginata to be the ‘Turbo marginatus, Nutt.’ of Reeve, and from this species as type, described the genus to be imperforate, etc. Unfortunately, Dr. Gray did not observe the error, which had arisen from confounding two different shells called marginatus; and in his guide to Mollusca (in loco) he adopts the description of Messrs. Adams; so that Collonia, Gray, (hodie) = Collonia, Add., but not Collonia, Gray, (olim). Of the species arranged by Mr. H. Adams under Collonia, some may belong to the original genus: some are included under Cynisca, A. Ad.; and one (Turbo phasianella, C. B. Ad.) appears to be Eucosmia. They appear in the Br. Mus. Col. distributed between Gibbula and Photinula. The true Turbo marginatus of Nutt. is the ordinary black Californian Chlorostoma, like mœstus, and well named from its frilled margin near the suture. But the label having become affixed to the T. marginatus Rve. (which must stand as Reeve’s species and not Nuttall’s) the Californian shell was left without name, and was described by Mr. A. Adams as Chl. funebrale, under which name it must stand as Nuttal’s prior name was (unfortunately) in MS. only. The name Collonia marginata must stand for the original fossil of Lamarck. It is probable that Reeve’s shell belongs to another group; else it must, according to the usual custom of honoring error, be called C. Reevei. For the Californian species, which are imperforate and have a thin, smooth operculum, Mr. A. Adams and I propose to form a subgenus Leptonyx; a diagnosis of which will appear in the next paper, after the foreign species have been examined. The following are the Californian forms.
Leptonyx sanguineus, Linn.
H. t. parvâ, solidâ, rubrâ, anfr. V. subtumentibus, suturis plus minusve impressis; costulis spiralibus plus minusve rotundatis cinctâ, quarum iv.-viii. in spirâ monstrantur; aperturâ subcirculari; columellâ t. adolescente foveâ basali et dente ut in ‘Modulo’ munitâ; adultâ, callositate tenui labiali, foveam tegente, obscure bidentatâ; labio tenui, continuo; umbilico nullo.